Download Pediatric equipment

Pediatric equipment
In this lecture we are going to discuss the kind of equipment
we- anesthesiologists- need to safely anesthetize a pediatric
patient.
These equipments are basically the same as the equipment
required for the adults; but pediatric patient would require
more attention for fine tuning and better outcome.
Warming devices
Temperature regulation is a greater problem in a child
than an adult because of the higher ratio of body surface area
to body mass.
Hypothermia may cause an infant to become acidotic and
apneic, and may alter the kinetics of medications.(1)
Wrapping
• It can reduce the radiant and convective heat losses.(1)
• Wrapping can be done by simple materials as the plastic wrap
used for food or by a sophisticated material as the space
blankets with reflective aluminized layers.
• Wrapping has the hazard of eliminating sweating as a
regulatory thermal mechanism, so hyperthermia may develop.
Radiant warmers
• Overhead radiant heating units are useful; but it always
carries the risk of skin burn. (1)
Warming water blankets
• Circulating water mattresses are useful in maintain
normothrmia in patients with body surface of 0.5 m2 which
means 10 kg of body weight or less, which makes it perfect
for a pediatric patient. (1)
• precautions to prevent possible surface burns:
 fluid temperature should never exceed 39⁰C.
 Avoid direct contact of the patient’s with the warming
blanket.
Warm air mattress
• The most useful devices for keeping pediatric patient warm,
because they can be wrapped around any part of the body.
• They keep body temperature by a combination of convection
with warm air and also the plastic wrapping which serves to
reduce the evaporative heat losses. (1)
Heat and moisture exchangers (HME)
(1)
• They preserve body heat, but they :
 Increase the resistance to breathing. So, there are small
sized HME Fit for pediatric, and they are not suitable for
spontaneously breathing patient.
 May clog with humidity over time.
Fluid warmers
• As a rule, We have to give the patient his requirement of
fluids warmed at least to body temperature.
• The effectiveness of fluid warmers in warming intravenous
fluids (or blood products) depends on the time that these fluids
are in contact with the warmer.
• limitations to use:
 It is not effective in reversing hypothermia in pediatric
patient, as with slow intravenous fluid therapy-which is
seen in the maintenance phase- the heat is lost along the
length of the intravenous tubing between the warmer and
the patient.(1)
 over heating the fluids, would lead to possibility of
RBC’s hemolysis.
Intravenous Therapy
 Rules for intravenous therapy
• An intravenous access should be established in all
anesthetized patients.(1)
• The infusion fluid container should not exceed the estimated
fluid deficit for a certain patient; unless a volume limiting
device is used.(2)
• All the lines should be purged, and preferably intravenous
air traps should be used, especially, in neonates and children
with known intracardiac defects.(3)
 When precise amounts of fluids need to be transfused,
electronic pumps and intravenous rate controllers are used.
 These devices should have precise volume limits, air bubble
alarm and pressure alarm.
 Another cheaper method for metered transfusion is the use
of a multiple stopcocks, with a syringe attached to one of the
stopcocks for a precise volume calculation.
 In emergencies, high flow rates through an intravenous line
are needed. A rapid transfusion devices that have rapid
warming and rapid administration features are the best
solution.
A cheaper solution, but less effective, is the pressure infusion
cuff that wraps around the solution.
Airway devices
Masks
• A face mask that is suitable for pediatric use would be:
 Small dead space, like Rendell-Baker/Soucek masks.
 Transparent masks help in observing the patient’s color and
shows condensation from exhaled water vapor.
Airways
• Oral airways
 It is a must in pediatrics as infants have large tongue.
 Infants from 1-2 years would require 7 cm airway, 2-8 years
an 8 cm airway, and over 8 years 9 cm. (1)
 If the airway is too large, it may result in uvular swelling or
epiglottitis and postoperative airway obstruction. (2)
• Nasopharyngeal airways
 These are not usually used in pediatrics as the internal
diameter of such airways are usually small, increasing the work
of breathing. Also, there is an increased risk of bleeding d.t.
adenoid hypertrophy.
 It can be replaced by an endotracheal tube cut to
appropriate length.
• Laryngeal mask airway (LMA)
 As in adults, LMA is a valuable airway device, it is used to
maintain airway in spontaneous breathing setting. (1)
 It becomes most valuable in the difficult to intubate, difficult
to ventilate scenarios.
Size
1
1 1/2
2
2 1/2
3
4
5
6
Pt.
selection
Neonate
<5kg
Infant
5-10kg
Child
10-20kg
Child
20-30kg
Child
30-50kg
Adult
50-70kg
Adult
70100kg
Adult
>100kg
Inflation
Volume
4ml
7ml
10ml
14ml
20ml
30ml
40ml
50ml
Endotracheal tubes (ETT)
• In pediatric O.R.; ETT with sizes ranging from 2 to 6 mm
internal diameter (ID) must be available, along with the
appropriate size stylets.
• The estimated size for a child older than 2 years is the patient’s
age divided by 4 plus 4.5 mm ID. A full term neonate would
accept a 3 mm ID, a normal 1 year old would accept 3.5-4 mm ID,
and a 2 year old 4.5 to 5 mm ID. (1)
• usually uncuffed tubes are used for elective surgeries, but
when a patient has a full stomach, hiatus hernia or non
compliant lungs a cuffed tube is used, and these are available as
small as 3 mm ID. (1)
• For head and neck surgeries, preformed tubes are used
putting the anesthesia circuit away from the surgical field.
Also, armored tubes are available whenever tube kink is a
possibility, but, the wire reinforcement adds to the external
diameter.
Intubation equipment
• For pediatric patient, laryngoscopes are available with small
lightweight handle and a full range of blades. Generally, a
straight blade design is often used in small children, infants
and neonates in sizes 2, 1, and 0 respectively. (1)
• Flexible and rigid fiberoptic laryngoscopes and
bronchoscopes are available for pediatric and used for patients
with difficult airway.
Anesthesia machine and
appendages
Anesthesia machine
• Most of the modern standard adult machines can be
adjusted for pediatric setting, it is not economic or necessary
to have anesthesia machine customized for pediatric use
only.
• The machine should have air flow meter for cases where
nitrous oxide or high inspired oxygen is contraindicated for
example in patients with intestinal obstruction and in
premature infants.
 Circuits and ventilators
• Infants and neonates less than 10 kg were anesthetized with
non rebreathing systems as the Mapleson D systems; which have
no valves or CO2 absorber which would greatly reduce the
resistance to breathing. one famous modification to it the
Jackson-Rees modification of Ayre’s T-piece.
• The main disadvantage of such system is the need for relatively
high fresh gas flow which leads to waste of anesthetic agents and
excessive pollution to the O.R.
• Nowadays, controlled ventilation is recommended, as it
allows the use of circle system even in neonates with the
advantage of lower fresh gas flow and therefore cost savings
and less pollution.
• Ventilators used in pediatric should be able to deliver
small tidal volumes, rapid rates in high accuracy, and
should have pressure limitation device.
• In children less than 10 kg, pressure controlled ventilation
may be preferred with peak inspiratory pressure of
15-18 cm H2O (1). In older children, volume controlled
ventilation can be used, with tidal volume set at 8-10 ml/kg.
in both conditions, the adequacy of ventilation should be
monitored .
• The tidal volume shouldn’t be only based on the weight, but
also on:
 chest wall expansion.
 breath sound auscultation.
observing the peak inflation pressure.
Equipment cart and
defibrillators
• The usage of mobile multi-drawer carts is very valuable in the
care of pediatric patients; especially that pediatric anesthesia is
often administrated outside the O.R.
• These carts are used to stock all the pediatric equipment and
supplies necessary to make the anesthetic practice safe.
• Defibrillators to be suitable for pediatric use should have
energy range that can be adjusted to the appropriate levels (1-2
jouls/kg), and a pediatric sized paddles.
Monitoring equipment
Anesthesia record
• The anesthesia record is important both in the medicolegal
aspects and as a monitor tool; documenting the patient’s
status on arrival, and evaluating every aspect of the patient.
• Many changes that are too subtle to interpret on moment to
moment basis, become obvious when plotted in the record
over time. (1)
Precordial/esophageal stethoscope
• it is a very valuable monitor. In infants, neonates and small
children, an experienced ear can easily diagnose arrhythmias,
assess cardiac output and adequacy of blood pressure.
• The optimal site where both heart and breath sounds can be
auscultated is the apex of the heart, sometimes the
suprasternal notch is used.
• After intubation, the precordial stethoscope can be changed
with an esophageal stethoscope, which is usually not traumatic
even in newborns. (1)
Blood pressure measuring devices
•Non invasive blood pressure measuring devices
 Blood pressure cuff should cover approximately two thirds
of the length of the upper arm and its bladder should be
placed on the artery. If the length and the size are wrong,
fallacies would occur.
 Blood pressure measure from the cuff wrapped around the
infant’s calf muscle poorly correlates with the arm blood
pressure.
 We should avoid prolonged inflation time, as this may lead
to venous stasis, petechiae, and possibly nerve compression
damage.
• Invasive blood pressure, central venous pressure, pulmonary
Artery pressure monitoring
 In infants and neonates, percutaneous arterial cannulation is
performed with a 22- to 24- gauge catheter-over-needle device,
with a 20- gauge device in older patients. (1) For central venous
and pulmonary artery cannulation, seldinger technique is used.
 The reference location for all pressures is the level of the
patient’s right atrium. (2)
 values of central venous catheter and pulmonary artery
catheter: helping in the management of air embolism in
operations in the sitting position, mixed venous sampling from
the pulmonary artery catheter to measure oxygen extraction,
and calculation of COP.
Balloon Inflation
valve
Electrocardiogram (ECG)
• ECG is a mandatory monitor. The lead placement may differ
in pediatric patient than in adult patient, as the primary need
for ECG in pediatrics is the diagnosis of arrhythmias rather
than the detection of ischemia.
• The lead should not become wet with preparation solutions
and should be isolated from the electrocautery dispersive
electrode to avoid electrical burn.
Oxygen monitor
• In neonates, especially premature, it is important to monitor
inspired oxygen concentration, so as to be able to blend air with
oxygen and prevent the possible ocular toxicity resulting from
high inspired oxygen concentration.
Temperature monitors
• Temperature monitoring is important to detect
temperature fluctuations, which is mostly hypothermia. (1)
• Monitoring site could be :
 Esophageal & nasopharyngeal probes: but when the patient
is intubated the esophageal probe may show lower value (2).
 Rectal probe: but it is subject to cooling during major
abdominal procedures.
Axillary probe: placed high in the axilla and no IV
fluids should be given in that arm. (1)
 Tympanic membrane probe: but improperly placed probe
may injure the tympanic membrane.
Pulse oximetry
• Pulse oximetry is by far the most important monitor in
anesthetic practice, its value: Measuring oxygen saturation value.
 Provides an early warning of developing desaturation
well before a clinician is able to detect it clinically. (1)
 Detecting arrhythmias and peripheral perfusion
inadequacy caused either by hypovolemia or hypothermia
by the waveform.
• Its accuracy is affected by:





Intravenous dyes and nail polish.
Dyshemoglobinopathies.
When O2 saturation becomes less than 70%.
Electrocautery, flickering or bright O.R. lights.
Movement of the patient.
Carbon dioxide analyzers
• Monitors that measure the end tidal CO2 work by 2 methods;
either suctioning the expired gas from the anesthesia circuit
(side-stream sampler), or acting as a main stream optical
sensor.
• The side stream samplers may become obstructed with water
or secretions; while the main stream is heavy and bulky leading
to the possibility of endotracheal tube kinking especially in
smaller pediatric sized tubes.
• Values of measurement of end tidal CO2 :
 Confirm endotracheal intubation.
 Adjust ventilatory setting, and confirm its adequacy.
 Detect complications like disconnections, ETT kinking,
accidental extubation, air embolism and malignant
hyperthermia.
Neuromuscular monitoring
• Whenever a muscle relaxant is used, neuromuscular
transmission should be monitored; best by assessing the
train of four.
• The infant sized ECG electrodes are the best electrodes used
to deliver the impulses, and the best location for these
electrodes is over the ulnar nerve with observation of the
thumb. (1)
Disconnection/apnea alarms
• Whenever a ventilator is used, a disconnection alarm
should be used especially in the absence of capnography.
These alarms sense time cycling of pressure events
• They may not be sensitive enough to detect extubations
with small endotracheal tubes or partial circuit
disconnections because of the continued presence of flow
resistance
Apnea monitors
• These are very helpful in the perioperative, and recovery room
period; especially in premature infants with less than 60 weeks
postconceptual age, infants with history of apnea spells
• These monitors depend on transthoracic impedance or
respiratory motion.
Inspiratory pressure gauge
• In patients requiring mechanical ventilation, especially the
pediatric age group, a pressure gauge applied at the airway
allows delivery of precise pressures and help to prevent
barotrauma. (1)
• The closer the measurement site to the airway, the more
accurate the pressure measured
Blood loss monitoring
• Blood loss estimation is best done by:
 Close observation of the surgical field and the patient’s
physiologic status.
 The use of a small volume tarp on the suction line before
the main evacuation trap is arranged. (1)
 Weighing surgical sponges making the approximation of
1 gm of weight equivalent to 1 ml of blood.
Urine volume monitoring
• U.O.P. is valuable for:
 Indicator of volume and perfusion status.
 If hematuria develops, it would indicate surgical trauma
to the urinary system, or transfusion reaction.
• The indications for urinary catheter insertion:
 Procedures with massive fluid shifts.
 Prolonged radiologic procedures with large doses of
contrast material.
 Diuretic therapy, and urinary reconstructive procedures.
Purchasing Anesthesia
Equipment
Useful principals for any equipment purchase: New equipment should be compatible and interface
with the equipment that is already present.
 The new equipment should be usable in different
locations (e.g. O.R. and ICU).
 Sales persons are biased, the reviews and info about a
certain device or brand name should be obtained from
unbiased sources, as research institute and boards.
 The proposed equipment should be tested in the same
working environment and by the same personnel who will
be using it.
 The hospital safety office should check for all the safety
issues regarding the use of this equipment.
 Spend as much on the maintenance as on the product.
Consider a maintenance contract.
 If two products are comparable, choose the one with
local service facilities.
 Consider the specific needs, for example if the monitor is
to be used for transport or outside the O.R. it must have
internal battery backup.
 Though economically difficult, additional spare units of
the same equipment should be available, as any given piece
of equipment will occasionally be out of service.
Questions
 To warm a 12 years old hypothermic child the best would be:
A) Water mattress.
B) Warm fluids.
C) Warm air blanket.
D) Over head warmer.
 Concerning pediatric airway, the following is true:
A) Nasal airway is better than oral airway.
B) Laryngeal airway has no role.
C) Curved and straight laryngoscope blades can be used.
D) Reinforced endotracheal tubes is a must.
 Concerning mechanical ventilation in pediatrics,
the following is true:
A) It is contraindicated in pediatrics.
B) The tubing has to be wide to decrease resistance.
C) It is more economic.
D) No role for volume controlled mechanical ventilation
 the value obtained from a pulse oximeter is not affected by:
A) Desaturation, less than 70%
B) Nail polish.
C) anemia.
D) Bright O.R. light and patient movement.